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Tuesday, September 18, 2012

The Case for Thorium

Japan's Nuclear Problem

Recently, news reports have indicated that Japan will be discontinuing their Nuclear power programs, this is not only startling but disheartening. As more and more coal burning plants are constructed CO2 gas emissions continue to rise and continue to increase the temperature of our global climate.

I know many will cite the fact that fissile waste material is dangerous and expensive to store and arguably worse pollutant than CO2, and that is a fair assessment, this is where Thorium comes in.

Before I make my case for Thorium I want to go over the some of the history of nuclear power and some of the reasons why it was relatively unsafe and why Thorium is safe and necessary if our species is to last on this planet with real quality of life in the future.

Part of the reason so many nuclear reactors were built in the 60s and 70s was to gain plutonium which in turn was used in nuclear weapons in the escalating arms race against the USSR.

Hundreds of water cooled fission reactors were built all over the world. Water cooled reactors were much more popular and can easily been observed with the large cooling towers and large containment structures around the reactor itself. In order to efficiently turn the turbines water is super-heated under pressure, if pressure were to be lost the liquid would flash into steam, a volume differential of over 1500 to 1. If the containment structure is too small, or if there is a leak, then water bearing radioactive material would enter the atmosphere.

Now not all is doom and gloom, even with our current nuclear technology, watt for watt nuclear power is the safest energy source currently in use claiming fewer lives per watt than any other power source.

Enter Thorium

Thorium has actually been used as a fuel for many years and there were several reactors built in the United States that operated without a significant accident. There are several reactors currently using Thorium as a fuel supply, for example the Indian 3-Stage Program. Thorium is the 39th most common element in the earth's crust making it readily available the however for Thorium to become fissile it must first be transmuted to Uranium 233. With current fission reactors this is possible and as with India's 3 stage process the first two stages are utilized to create the thorium fuel used in the final stage.

The Thorium molten salt reactor design was championed by Dr. Alvin Weinberg of Oak Ridge National Laboratory. Originally designed for use in long range aircraft and known as the "chemist's reactor" Oak Ridge studied and experimented with the Molten Salt Thorium Reactor for many years until 1973 when Dr. Weinberg was fired by the Nixon administration. Dr. Weinberg was fired because he wished to continue pursue Thorium and Molten Salt research but the administration wished to research the riskier Liquid Metal Fast Breeder Reactors. After Dr. Wineberg's departure from Oak Ridge Thorium research in the US waned.

Resurgance

Interest in Molten Salt Reactors powered by Thorium fuel has recently increased due in large part to the efforts of Kirk Sorensen who came upon the idea while attempting to design a power source for the Moon. He found that there is a great amount of Thorium on the Moon and although there is no atmosphere allowing solar energy to work well there is a two week night while the Moon orbits the Earth making solar energy much less effective due to current battery storage technology. While researching methods of nuclear power generation he found a book dealing with Thorium reactors from the early days of Nuclear Power.

Safety

We worry about nuclear meltdowns, or environmental issues causing problems with nuclear plants (fukushima in japan for example) or spent fuel disposal issues. Although the odds of another Chernobyl or 3-mile island occurring are very small there is a possibility with ageing infrastructure and cost cutting. If a water cooled nuclear reactor loses the ability to circulate it's coolant it can melt down or breach, if a Thorium powered Molten Salt Reactor loses the ability to circulate the Molten Salt coolant a salt plug at the bottom of the reactor will melt and the liquid will drop into a small containment system below the reactor. Because Molten Salt will not boil and does not require expansion if there is a loss of pressure. Japan has publicly stated that they are going to be steering away from nuclear power but are considering Thorium as an answer.

More Power To you!

~Yati

Below I have provided several links to additional information as well as Kirk Sorensen's Ted Talk about Thorium Reactors